Beaches
MWRA assists Massachusetts Department of Conservation and Recreation (DCR) in testing water quality at Carson, Constitution, Tenean, Pleasure Bay, and Wollaston beaches.

Boston Harbor & Rivers
The Massachusetts Water Resources Authority's (MWRA) has been monitoring water quality in Boston Harbor and its tributaries since 1989. MWRA makes at least 20 visits to each sampling location every year. Monitoring areas are: Charles River, Mystic River/Alewife Brook, Inner Harbor, Northern Dorchester Bay/Carson Beach, Southern Dorchester Bay/Tenean Beach, Neponset River, and Quincy Bay/Wollaston Beach.

Combined Sewer Overflows
The Combined Sewer Overflow (CSO) monitoring area includes the "receiving waters" of all CSO communities in greater Boston including the Inner Harbor, Boston Harbor embayments, and tributary rivers. Measurements include bacteria, nutrients, dissolved oxygen, and water clarity.

Summary of CSO Receiving Water Quality Monitoring in Upper Mystic River/Alewife Brook and Charles River

CSO Sampling Map

More information on CSOs

Data Analysis & Interpretation
Long-term Harbor monitoring helps in identifying change in water quality over time. Historical results from 1989 to last year for bacteria, nutrients, and other water quality parameters are available for download in Excel spreadsheets for Boston Harbor and three tributary rivers. Summaries and technical analysis of MWRA water quality monitoring in Boston Harbor and Massachusetts Bay are available for download on our Technical Reports List.

Massachusetts Bay
MWRA's NPDES discharge permit for the Deer Island Wastewater Treatment Plant requires extensive monitoring and reporting. MWRA monitors the effluent (treated sewage) that is discharged into Massachusetts Bay, to ensure that it meets the standards set out in the permit. The Bay bacteria monitoring program measures water quality near the outfall to ensure that there is no risk to shellfish consumers.